Fixing tutorial_interaction with ParticleSetView

Author: erikvansebille

docs/user_guide/examples/tutorial_interaction.ipynb

@@ -293,18 +293,9 @@
     "    larger_idx = np.where(mass_j > mass_i, pair_j, pair_i)\n",
     "    smaller_idx = np.where(mass_j > mass_i, pair_i, pair_j)\n",
     "\n",
-    "    # perform transfer and mark deletions\n",
-    "    # TODO note that we use temporary arrays for indexing because of KernelParticle bug (GH #2143)\n",
-    "    masses = particles.mass\n",
-    "    states = particles.state\n",
-    "\n",
     "    # transfer mass from smaller to larger and mark smaller for deletion\n",
-    "    masses[larger_idx] += particles.mass[smaller_idx]\n",
-    "    states[smaller_idx] = parcels.StatusCode.Delete\n",
-    "\n",
-    "    # TODO use particle variables directly after KernelParticle bug (GH #2143) is fixed\n",
-    "    particles.mass = masses\n",
-    "    particles.state = states"
+    "    particles.mass[larger_idx] += particles.mass[smaller_idx]\n",
+    "    particles.state[smaller_idx] = parcels.StatusCode.Delete"
    ]
   },
   {

src/parcels/_core/particle.py

@@ -343,10 +343,17 @@ def _to_global_index(self, subindex=None):
             if isinstance(subindex, (slice, int)):
                 rel = np.flatnonzero(base)[subindex]
                 return rel
-            # otherwise assume subindex is an integer/array selection relative
-            # to the local view and map to global indices
+            # If subindex is an integer/array selection (relative to the
+            # local view) map those to global integer indices.
+            arr = np.asarray(subindex)
+            if arr.dtype != bool:
+                particle_idxs = np.flatnonzero(base)
+                sel = particle_idxs[arr]
+                return sel
+            # Otherwise treat subindex as a boolean mask relative to the
+            # local view and expand to a global boolean mask.
             global_mask = np.zeros_like(base, dtype=bool)
-            global_mask[base] = subindex
+            global_mask[base] = arr
             return global_mask
 
         # If base is an array of integer indices